[SOLVED] 'enum class' with QVariant (How to register strongly typed enum with Qt Meta System?)

[Resurrection]

Solution: Registration of mata-type was not an issue. QVariant does not have constructor taking a template value. In order to use it with custom types from Qt Meta System QVariant::seValue must be used.

Hi,

I have been searching but nothing I found worked for me (using Qt 5.3beta) so I figured to ask a new question.

How to register strongly typed enum with Qt Meta System?

I have:

@
class MyEnums : public QObject
{
//Q_ENUMS(Enum)
public:
enum class Enum : int
{
A,
B,
C
};
};

Q_DECLARE_METATYPE(MyEnums::Enum)
@

and then elsewhere

@
void Class::foo()
{
QVariant var(MyEnums::Enum::A);
}
@

which gives me compile error.

Using

@
qRegisterMetaType("MyEnums::Enum");
@

also does not work and it tells me the type is not registered and I should use Q_DECLARE_METATYPE macro which I clearly did though...

Switching to regular enum (i.e. 'enum' instead of 'enum class') works however.

Also I will require to register the enum with Q_ENUMS as well (as indicated in the first snippet). I am pointing it out in case it could be the problem too.

Thanks for help!

[Xander84]

Hi, it works fine with "enum class" and Q_DECLARE_METATYPE in my app, I have also used Q_ENUMS but I think that is only necessary because I use the enum values in QML.
Is it working if your remove the int type?
I mean
@
enum class Enum // : int
@
I did not change the type, but I thought "int" is the default type anyway so it should be exactly the same code if you write " : int" or omit it?

[Resurrection]

Oh I was so dumb... I did not notice that no constructor of QVariant is taking template type. In order to use it with custom types registered QVariant::setValue has to be used instead.

[Xander84]

Oh sorry I noticed that befre but thought it would also work, I guess you can't use the QVariant constructor for custom types, so replace
@
QVariant var(MyEnums::Enum::A);
@
with
@
QVariant var = QVariant::fromValue(MyEnums::Enum::A);
@
and it should work :)

Edit: haha you changed your post while I was compiling your project, anyway you can use the static function QVariant::fromValue instead of setValue, so this post is not entirely useless i guess. :D

[Resurrection]

Sorry for changing my post, I figured it was redundant given such a simple mistake.

And thanks a lot for your help! Incidentally that static function you pointed out is actually more useful to me than setValue. :-)